Study: Number of Pills Prescribed Is a Stronger Predictor of Opioid Consumption Than Pain Severity Postsurgery

Friday, November 16, 2018

Study: Number of Pills Prescribed Is a Stronger Predictor of Opioid Consumption Than Pain Severity Postsurgery

According to psychologists, humans have a tendency to make decisions based on an overreliance on a single value, to such a degree that other values are minimized or ignored entirely. It's called the "anchoring and adjustment heuristic," and it's not uncommon: we tend to eat more food than normal (the adjustment) if we're presented with larger quantities of it (the anchor); we tend to think we're getting a good deal on something we're shopping for (the adjustment) if the price is lower than the one we've fixed in our minds, which is often the first price we saw (the anchor).

Now researchers are wondering if this behavior phenomenon plays an even more insidious role when it comes to opioid use—namely, a tendency for patients to take more opioids if they're prescribed larger quantities of pills. That's what authors of a new study discovered after conducting patient surveys that revealed postsurgical opioid consumption rose by an additional 5 pills for every 10 prescribed. In fact, they claim, the relationship between opioids consumed and opioid quantities prescribed is stronger than the link between the level of pain experienced by patients postsurgery and their opioid consumption.

The results, published in JAMA Surgery (abstract only available for free), are based on surveys of 2,392 patients in Michigan who were prescribed opioids after undergoing 1 of 12 targeted surgeries including cholecystectomy, appendectomy, femoral hernia repair, incisional hernia repair, colectomy (laparoscopic and open), ileostomy and colostomy takedown, small-bowel resection, thyroidectomy, and hysterectomy (vaginal and abdominal). Researchers conducted phone interviews with patients during a window between 30 days and 120 days postsurgery, asking them how many opioid pills they had consumed and gathering self-reports on pain using a 4-item scale. They then analyzed patients' answers in relation to various demographic variables, surgeries received, and oral morphine equivalents (OMEs) prescribed.

Here's what they found:

The strongest predictor of opioid consumption was the amount of opioids prescribed to the patient. Researchers estimate that for each additional OME prescribed, patients used an additional 0.53 OMEs. Put in terms of pill equivalents, that's equal to using 5.3 more pills for every 10 additional pills prescribed. "A patient prescribed 100 pills could therefore be expected to use roughly 40 more pills than a patient prescribed 20 pills," authors write.

While pain severity also was linked to increased consumption, the relationship wasn't a strong as the tie to quantity of pills prescribed: compared with patients reporting no pain postsurgery, those reporting moderate pain used an additional 9 pills, and those reporting severe pain reported using an additional 16 pills, on average.

Tobacco use and obesity were related to increased opioid consumption; outpatient surgery was associated with decreased consumption, as was older age.

Overall, 24% of patients reported taking no opioids after surgery. The highest rate of nonuse was among patients who underwent thyroidectomy (48% nonuse rate) and lowest was for the group receiving abdominal hysterectomy (20% nonuse rate).

Consumption of the entire opioid prescription was reported by 22% of patients interviewed.

In all surgeries studied, the quantity of opioids prescribed was "significantly greater" than the quantity of opioids consumed, with an average of 30 5/325 mg of hydrocodone/acetaminophen pill-equivalents prescribed compared with an average of 9 pills taken. Consumption ranged from 3% of opioids prescribed following thyroidectomy to 67% of opioids prescribed after ileostomy/colostomy takedown.

Mean age of the respondents was 55, with 57% women; 77% underwent elective surgery as opposed to urgent or emergent surgery. Three surgical procedures made up more than half of the total surgeries analyzed: hernia repair (28%), cholecystectomy (25%), and appendectomy (9%).

Researchers acknowledge that there may be a link between postsurgical consumption and preoperative opioid use—data they weren't able to gather—but they believe the key to their findings my lie with the anchoring and adjustment heuristic.

"In this case, a larger amount of opioids may serve as a mental anchor by which patients estimate their analgesic needs," authors write. "The amount of opioids a surgeon prescribes to a patient may influence that patient's opioid consumption after surgery."

Also concerning, according to the authors, is that the complete opioid prescription is seldom consumed—at least as part of recovery postsurgery. What's worse, "most patient who received opioids after surgery do not dispose of leftover medication," they write, adding that "it is well established that most individuals who misuse prescription opioids obtain the medication from a friend or relative as opposed to 'doctor shopping' or illicit sources."

While the researchers think their findings may help in better customizing prescriptions based on individual patient variables, they believe there's an even more obvious first step that needs to be taken immediately: stop prescribing so many opioids, period.

"Overprescribing occurred for all procedures included in this study, from relatively minor to major operations," authors write. "These data highlight the importance of significantly changing the way opioids are prescribed following surgery to decrease excess medication as a source for diversion and abuse."

findings reported in the JAMA article echo the conclusions of a recently updated report from the Plan Against Pain, which asserts a link between opioid prescriptions postsurgery and later opioid dependence. APTA's #ChoosePT opioid awareness campaign is a selected partner of the plan.

Research-related stories featured in PT in Motion News are intended to highlight a topic of interest only and do not constitute an endorsement by APTA. For synthesized research and evidence-based practice information, visit the association's PTNow website.